PORT ST. LUCIE — Just when the Mets thought they might escape spring training without a significant health concern in the rotation, Steven Matz’s elbow started barking.

The fragile lefty has been scratched from his scheduled Monday start in a minor league exhibition game because of “irritation” in his elbow that could preclude him from beginning the season with the club.

Matz was recently examined by team doctors and assured there is no ligament damage in the elbow, according to general manager Sandy Alderson, but the prognosis remains unclear. In the meantime, the Mets plan to evaluate Zack Wheeler and Seth Lugo to occupy Matz’s rotation spot.

Matz called the situation a “little setback” and said he plans to test the elbow in a throwing session on flat ground Monday.

“Before my last start it was a little tender and then into the last start it was just more sore than normal,” Matz said.

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It’s just the latest physical issue for Matz, who missed the final six weeks of last season with a shoulder impingement after pitching for most of the summer with a significant bone spur in his elbow, which was removed in October.

Matz missed two months in 2015 with a partially torn lat muscle.

“It’s worrisome that he continues to be injured off and on, that is the difficulty,” Alderson said. “We don’t think it’s serious. On the other hand, starting pitchers, we rely on them every five days. We’re not sure where this is going to take us, but he won’t pitch [Monday].”

If Matz can’t begin the season with the club, the Mets have other viable options in Wheeler and Lugo, with Robert Gsellman already penciled into the rotation behind Noah Syndergaard, Jacob deGrom and Matt Harvey.

Lugo and Wheeler will both pitch Monday in split-squad games. Lugo is scheduled to face the Nationals at First Data Field, and Wheeler will pitch against the Marlins in Jupiter, Fla.

“As much as we want Steven in the rotation, as much as we think he’s going to be a tremendous pitcher, we’ve got to make sure that his arm is cleaned up,” manager Terry Collins said. “Because we don’t want to go through what we did last year where almost every time it was getting for his turn you didn’t know if he was going to make it or not. You have to make sure we can run him out there every five days.”

Wheeler, who missed the last two seasons rehabbing from Tommy John surgery, has impressed team officials with his velocity, but the right-hander’s command is still an issue. In his relief appearance Wednesday against the Marlins, he allowed four earned runs on four hits over three innings.

Lugo will be pitching in his first Grapefruit League game since returning from the World Baseball Classic, where he represented Puerto Rico. The fact that Lugo can pitch out of the bullpen intrigues Collins, and the righty might be a better fit in a relief role, especially as the Mets await MLB’s ruling on Jeurys Familia, who is expected to receive a suspension following his offseason arrest on domestic violence charges.

“We had a backup plan, and we’re going to turn to that backup plan right now,” Collins said. “Hopefully Zack comes out [Monday] and shows us that he’s advancing, and if Steven can’t start the year — it’s going to be tough for him, I think, if he’s not going to pitch this week. We’re just lucky we have some pretty good pitching.”

Wheeler is facing an innings limit in the 120-125 range, but Collins said it’s not an issue that will affect the potential Opening Day roster.

“Right now I don’t think we should concern ourselves with innings limits,” Collins said. “If we think Zack is the guy, it might be a situation if you’ve got to pitch him, you’ve got to pitch him. And we’ll worry about those innings limits in the middle of summer.”